Noble Metal Oxides Electrodes and Analytical Application Thereof for Acid-Base Titrations in Non-Aqueous Solvents

Abstract

Electrochemical characterization of palladium and platinum oxide electrodes is reported. Palladium (platinum) oxide layer has been formed by thermal oxidation of smooth Pd(Pt) electrode. The palladium/palladium oxide electrode enables fast measurements, with good sensitivity of 54 ± 0.9 mV per decade, in acidic and base solutions (linear range of response up to the concentration 1 × 10 −6 M) in acetonitrile and 49 ± 1.2 mV per decade in propionitrile. The response of the platinum/platinum oxide was linear in the concentration range between 5 × 10 −2 and 1 × 10 −6 M, and a sensitivity of 52 ± 1.6 mV per decade in acetonitrile was obtained. The response time of the electrodes was less than 15 s in the both solvents. The properties of the palladium oxide electrode were similar to those of the platinum one. Some potential analytical applications of the sensors are pointed. Palladium and platinum oxide electrodes for the potentiometric titrations of acids (benzoic, anthranilic, salicylic acids, and sulfadiazine) and bases (N,N -diphenylguanidine, tributylamine, and collidine) in acetonitrile and propionitrile were studied. Potassium hydroxide, tetrabutylammonium hydroxide and perchloric acid proved to be very suitable titrating agents for these titrations. The standard deviation of the determination of the investigated acids and bases was less than 0.7% from those obtained with a glass electrode. The electrodes have the following advantages: fast response, and reproducibility, the service life is long and without considerable divergence in potentials, the manufacture is simple, the production cost is low.

TiO2‐modified Carbon Paste Electrode as a Sensor for the Assay of Weak Organic Acids/Bases and Complex Matrix Samples

“…The first step of this study was to analyze the characteristics of the TiO 2 ‐modified electrode and some aspects of its practical implementation. The results support the assumption that the TiO 2 ‐modified electrode can be applied in the process of determination of some compounds isolated from natural products presenting acidic properties, determination of biological materials and, most importantly, determination of some analytes in non‐aqueous solutions where a glass electrode shows disadvantages, well known from the literature 5. Some preliminary tests indicate that using TiO 2 ‐modified electrode in non‐aqueous solutions requests a small modification – mineral oil has to be replaced by silicon oil.…”

“…The potentiometric response obtained for the PtO 2 electrode is 46.7 mV/pH in the pH range of 3.0–11.0, while the RhO 2 is 68.2 mV/pH in the same area. Furthermore, PdO and PtO 2 sensors are applied in a non‐aqueous environment for the determination of the weak acids and bases 4, 5. Niedrach 6, 7 first applied ZrO 2 ion‐selective electrode for measuring the pH.…”

Natural mineral pyrite and analytical application thereof in precipitation titrations in non-aqueous solvents

“…The apparatus used to follow the potential changes of the pyrite electrode over time and for end-point detection with a pyrite electrode-SCE couple was described in an earlier paper. 30 The potential changes during titration were monitored using a Digital 870 pH-meter, Dresden. The stirrer, the burette and the glass vessels were standard equipment.…”